Blends of polycarbonate (PC) and polyester (P*T where * refers to an olefin such as ethylene or butylene) are well known as engineered polymeric materials. Often PC/P*T blends are impact modified. For example, European Patent Publication EP1207172A2 discloses an improved impact modifier for blends of polyester with other polymers, including polycarbonate, wherein the impact modifier itself is a blend of a core/shell additive and a linear copolymer of olefin, alkyl acrylate, and glycidyl methacrylate monomers.
PC/P*T blends can also benefit from flow enhancers to improve processing properties of the blend. U.S. Pat. No. 6,599,966 (Penning et al.) discloses polycarbonate-polyester compositions with enhanced flow. The flow enhancing additives are selected from lignin and phosphonium sulfonate.